Before dealing with this question it may be appropriate to present graphically the mortality of general paresis in Copenhagen in the period of 1866–1935 (see Fig. 1).

1. Details have been given of the cancer mortality for twelve occupational groups of males in the City of Sheffield 1926–35 inclusive.

2. Of these groups six show a significantly greater cancer mortality than that experienced by clerks, business and professional men in the City. The six groups are:

(1) Engineers, machinists, cutlers, etc.

(2) Steel foundry and furnace workers, etc.

(3) Grinders and sandblasters.

(4) Workers in precious and non-ferrous metals.

(5) Workers in transport and communication.

(6) Coal miners.

3. The excessive cancer mortality in certain of the sites in the first three of these occupational groups is thought to be definitely associated with their occupation.

4. Cancer of the tonsil is particularly excessive among the steel workers both in the foundry and the shop.

5. Significantly excessive mortality from cancer of the respiratory tract is marked in engineers, foundry workers and grinders and is seen in no other occupational group.

6. Cancer of the alimentary tract is most excessive in foundry and furnace workers. It is suggested that the carcinogenic factor may be hydrocarbons ingested from smoke and fumes.

7. Cancer of the pancreas is excessive only in engineers, etc., and in workers in non-ferrous metals. The theory is advanced that excessive absorption of iron in engineers, and possibly copper in workers in non-ferrous metals, are the respective causes of the findings with regard to cancer of the pancreas in these two occupational groups.

8. Cancer of the skin is significantly excessive in both foundry, etc., workers and engineers, and this is believed to be a direct result of their occupational environment.

9. Tumours of the central nervous system showed no significant variation from the control in any occupational group.

10. The findings in this research indicate that there is a field for further investigation with regard to the carcinogenic properties of iron and copper, particularly with reference to cancer of the pancreas. Some further investigation is re uired with reference to the occupations exposed to the inhalation and ingestion of silica. Is the high cancer rate amongst grinders associated with the silica risk or with the inhalation and ingestion of iron dust from the article ground? On the preventive side the findings support the view that measures should be elaborated to improve the protection of workers from gases, fumes and dust in the iron and steel and allied industries.

The literature dealing with the intradermal test in whooping cough has been reviewed, and the claims as to the specific value of the test have been investigated in 1300 cases.

A method for the extraction of endotoxin from Haemophilus pertussis has been described and the intradermal response to this preparation compared with that following whole vaccine.

The findings in this investigation do not support the claim that the intradermal response to Sauer's vaccine in the strength commonly employed (10,000 million organisms per c.c.) is of value either in demonstrating immunity to whooping cough or in the early diagnosis of this disease. The bacterial content of this vaccine appears to be too high for skin-testing purposes, giving rise to inflammatory lesions of a non-specific character rather than to allergic reactions of specific value. These reactions are less apparent when the vaccine is employed in a diluted form.

The intradermal response to pertussis endotoxin, on the other hand, though not invariably consisting of a clear-cut reaction (and in this respect falling short of the ideal as a reagent) is more consistent with the development of the allergic state towards H. pertussis, reactions presumably of this nature being present in the skin of approximately 85% of children with a past history of whooping cough. Similar reactions, however, can be elicited in the skin of about 30% of individuals with no history of the disease; but in view of the fact that, unlike the more invasive virus diseases, many individuals never develop whooping cough in spite of almost certain exposure when young, it is suggested that latent immunization or recent contact with the causative organism might account for this phenomenon. Whether these reactions indicate merely sensitization or a definite immunity to pertussis must remain, for the time being, sub judice.

The onset of bacterial hypersensitiveness, as judged by the pertussis endotoxin test, appears about the 10th day of whooping cough and becomes heightened during the subsequent course of the disease. Ultimately this cutaneous allergy undergoes a regression, which, however, is not always complete. For this reason the pertussis endotoxin test would appear to be of some value in assessing the immune state of the individual, and also as a diagnostic reaction in early, atypical or late cases of whooping cough where bacteriological findings by the cough plate method have proved disappointing.

An investigation is described which shows the type of skin reaction which may be expected from the intracutaneous injection of 0·1 c.c. normal horse serum in the normal and sensitized human subject. 150 normal individuals and 100 who had received previous serum injection were skin-tested. Of the normal subjects 30% showed a reaction of skin sensitivity, while 88% of the sensitized group gave a sensitive response, the reactions in the latter being more intense and of longer duration than those of the normal group. It is also shown that general skin sensitivity, demonstrated by a sensitive skin reaction in the opposite arm 2 weeks later, can be produced by intracutaneous injection of 0·2 c.c. of normal horse serum.

The value of specific skin tests in the prognosis of serum reaction is considered and a series of tests on 200 diphtheria cases is recorded. Since it has been shown that diphtheria has no appreciable effect in diminishing skin sensitivity (Westwater, 1935) the present series probably gives an accurate estimation of serum skin sensitivity even in the presence of acute diphtheritic infection.

The incidence of serum reaction was found to be only 6% higher in those cases which gave a sensitive skin reaction to horse serum prior to therapeutic serum injection than in those showing a normal response. It is therefore concluded that the demonstration of skin sensitivity is of no value in predicting the subsequent development of general serum reaction, and skin testing with horse serum, although it may demonstrate the presence of specific antibodies in the skin cells, is not an index of general sensitivity, which depends upon individual reactivity and power to produce antibodies following injection of foreign serum.

1. The diets of 120 pregnant women at different economic levels have been studied by the individual method.

2. The intake of calories was found to be little affected by income, and this was true also of fat and carbohydrate. The intakes of protein, animal protein, calcium, phosphorus, iron and vitamin B1 rose convincingly with income.

3. These differences were due to the fact that a rise in spending power led to an increased consumption of milk, fruit, vegetables and meat, and to a decreased consumption of bread and total cereals. Details are given in Table V.

4. Women taking the better diets were found on average to be taller and less anaemic than those taking the poorer diets. The differences were significant.

5. A comparison of the diets of the well-to-do women with the requirements suggested by the League of Nations and other authorities suggests that the requirement for calories has been set too high. The intake of calcium was suboptimal throughout and the diets of the poorer women were deficient in many respects.

1. An account is given of enteric fever in a Mental Hospital, and the discovery of a “precocious carrier” of the Bact. typhosum, a man who, 4½ months before he showed symptoms of the disease, was a “carrier” and probably the source of infection in a milk-borne outbreak.

2. Description of a strain of Bact. typhosum forming dwarf colonies which was isolated (a) from a river, (b) from a patient who had drunk the water, (c) from the sewage of a mental hospital discharged into the river 4½ miles higher up, and (d) from patients in the mental hospital.

3. Isolation of the Bact. typhosum from a well of an institution in which an outbreak of enteric fever had occurred.

4. Isolation of Bact. typhosum from a stream adjoining a well in a farmyard in Belfast at a time when the milk was the source of infection of over 100 cases of the disease.

5. Isolation of Bact. typhosum from a cesspool discharging into a stream near Bournemouth, and the suggestion that Mrs A. from whose premises milk was obtained, which was the infective vehicle in the Bournemouth-Poole epidemic, may have been a “precocious carrier”.

6. An account of methods employed in the bacteriological examination of water and sewage.

The investigation deals with the bacteriological examination of 386 samples of water from Manchester swimming baths where the method of purification could be studied.

There were 339 samples from chlorinated pools of which 160 gave acid and gas in MacConkey broth at 37° C. and 2130 strains were isolated. The remaining forty-seven samples were from untreated open-air pools. Thirty of these samples were positive and 270 strains were isolated. The strains were classified according to Wilson's method into the coli, intermediate, aerogenes and irregular groups, and only 1·78% of the total were found to be irregular. Both series of samples included more than 72% which contained coli, and among the chlorinated samples no less than 70% yielded aerogenes and nearly 49% intermediate type, while among the non-chlorinated baths there were 43% with aerogenes and 40% with intermediate type. There was a similar difference in the proportions of coli, aerogenes and intermediate type in chlorinated and in non-chlorinated baths when the results were considered on the basis of strains (Table II).

Since these differences in proportion were considered significant, and since the chief variation in conditions between outdoor and indoor baths consists of chlorination, a series of experiments was devised to test the effect of chlorine on pure cultures of coli, aerogenes, and intermediate type. There was very little change after adding 0·1 part of chlorine per million, but the addition of 0·3 and 0·5 part was followed by very rapid reduction in numbers with diminution in free chlorine. This reduction was on the whole least with aerogenes. The numbers continued to fall for about 48 hr. until all trace of chlorine had disappeared and then regrowth occurred. This regrowth was most vigorous and most rapid with aerogenes (see figures) but was very slow in all cases.

1. Feeding tests on monkeys (Macacus rhesus), dogs and cats are unsatisfactory for detecting the presence of enterotoxin, owing to the variable susceptibility of these animals by the oral route.

2. Using Dolman's method, in which the material is injected intra-peritoneally into kittens, the production of enterotoxin has been demonstrated by: (a) sixteen out of thirty-eight strains of Staph. aureus, isolated from cases of acute or chronic mastitis or from normal udder milk; (b) four out of five strains of Bact. coli, mostly from calves with “white scours”. No enterotoxin was obtained from fifteen strains of Str. agalactiae from mastitis in cows.

3. The formation of enterotoxin under natural conditions has been observed: (a) In udder milk seeded with Staph. aureus or naturally contaminated with that organism and stored at atmospheric temperatures (18 and 22°C.). The substance remains active in cheese prepared from such milk. (b) In layer cake made with cream naturally contaminated with Staph. aureus.

4. A small outbreak of poisoning due to potted meat paste was shown to be caused by a non-haemolytic Staphylococcus.

5. A few feeding experiments on man with milk or cream, in which food-poisoning staphylococci had grown, were negative, but on one occasion a Staphylococcus from a case of mastitis yielded a culture filtrate which caused symptoms of food poisoning.

6. Enterotoxin has the following properties. It is resistant to heat (95°C., 30 min.), to low concentrations of formalin sufficient to destroy the haemolytic toxin, to acid (pH 5·0), and to rennet, but is destroyed by trypsin.

It diffuses freely into the culture medium but only slightly through collodion. It is antigenic. Its properties are such that enterotoxin can be classed as a bacterial exotoxin.

Various authors have stated that the plague problem in Uganda is intimately connected with the cotton industry. Thornton sums up their statements: “as at present conducted the industry is a peril to other countries and to the peasants of Uganda themselves on account of plague”. The evidence given in support of these statements is vague and unconvincing and Roberts has investigated the question and come to an entirely different conclusion.

The object of this investigation is to gain more precise information concerning the retention of potency of vaccine lymph at those temperatures which are likely to be encountered by lymph after issue from the laboratory and before use by public vaccinators. These temperatures are—broadly speaking—likely to be those of the ice-box (say 5–7° C.) and average room temperature (say 15–16° C.).

An outbreak in May 1937 of about 130 cases of mild Sonne dysentery with no deaths. The outbreak was spread by ice-cream made under very unsatisfactory conditions, but no carrier case or specific source of infection ascertained. The very scattered nature of the outbreak, involving five different sanitary areas, with place of preparation in a sixth, is a feature of interest.

The survival rate, p, of a measured inoculum of Staph. aureus in a standard volume of denbrinated blood, is a reliable quantitative measure of the bactericidal power of blood. The number of viable organisms in the inoculum and in the blood-bacterium mixture may be estimated with the necessary accuracy by counts of colonies developing from measured volumes of the fluids let fall on to the surface of solid media. Fildes' agar was the most suitable medium for this surface-viable count, and was selected on the basis of four criteria; of the media tested it yielded the highest counts, and the counts conformed most closely to a Poisson series; and on it the mean colony size was maximum, and the coefficient of variation of colony size was minimum. On this medium, the close conformity of the separate count values to a Poisson series enabled the standard error of the survival rate to be determined from a simplification of the general expression for the standard error of a ratio.

The number of colonies growing from a sample of a blood-bacterium mixture may be reduced, not by killing of the individual cocci, but as a result of their aggregation either by agglutinins in the blood, or in the cytoplasm of leucocytes that are phagocytic but not bactericidal. It appears that these mechanisms are unlikely to operate in blood-bacterium mixture containing relatively few organisms; in such mixtures the survival rate is a reflexion of the killing power only.

The immunological significance of p has not been investigated, but the range of values for healthy human adults differs significantly from that for sufferers from chronic staphylococcal infection. Moreover, by the technique employed differences may be detected between individual values of p that cannot reasonably be attributed to technical or sampling errors.

1. Evidence is adduced to indicate that cross infection occurred in 36·6% of a series of 246 patients in diphtheria wards.

2. In patients who were in hospital longer than 2 months it occurred in 68%.

3. Persistence of diphtheria bacilli in the upper respiratory tract was responsible for prolongation of hospitalization in 76% of cases in a series examined.

4. In 80% of these cases this persistence was a result of cross infection.

5. The administrative importance of cross infection is discussed.

An account has been given in a previous paper of the immunizing procedures now employed in the preparation of anti-typhoid serum in the horse for therapeutic use in man (Felix & Petrie, 1938). The object of the present communication is to describe the methods used for the titration of the serum.

1. Examination of several hundred eggs suggests that a high proportion (98%) of the whites of fresh eggs, and a slightly smaller proportion of the yolks (93%), are sterile.

2. The shell of the egg is heavily infected with a heterogeneous flora, including Proteus and Pseudomonas bacteria capable of producing rotting.

3. The rots found in imported New Zealand and Australian eggs, and in English stored eggs, may be grouped into black rot, red rot, green rot, and a miscellaneous group.

4. Black rot is brought about chiefly by strains of Proteus, but some species of Pseudomonas cause some blackening. Red and green rots are due to infection with particular strains of Pseudomonas.

5. A “fishy” odour is developed during the multiplication of certain atypical coliform organisms in the white, and a strong “cabbage-water” smell is often found after the growth of Pseudomonas species.

6. Washing eggs under clean conditions has no effect on immediate bacterial penetration. Washing removes a protective coating so that if the eggs are subsequently soaked in a bacterial suspension, much more penetration of bacteria occurs than with untreated controls.

7. Detailed descriptions of the coliform and Proteus organisms isolated are given. It is shown that the strains of Proteus from the eggs here investigated are antigenically not related to P. melanovogenes found by Miles and Hainan to be the cause of black rot in South African eggs.

8. It does not at present seem possible to assign specific names to the organisms isolated. The utilization of carbon sources by the species of Pseudomonas obtained from eggs, and by certain stock strains, and the possibility of a grouping on that basis, is discussed.

One of us (S. L. C.), with C. Weatherall and E. T. Waters, published in 1931 the results of some experiments on the adsorption of the active principle of tuberculin by the dust of anthracite coal and showed that the activity of a diluted tuberculin was greatly diminished after contact with pulverized anthracite. In view of this fact, we made the suggestion that some such adsorbent action of autotuberculin by the finely divided coal-dust retained in the lung tissues of silico-anthracotic coal-miners might, perhaps, explain the relative freedom of these latter from the progressive pulmonary tuberculosis so commonly noted as a sequel to silicosis in gold-miners and others exposed to silicious dust free from admixture with coal-dust. These experiments have since been repeated by us with similar results and we, therefore, planned to try out the adsorption effects of other dusts liable to be inhaled in the course of coal-mining in South Wales.